8000 Speed up plpgsql trigger startup by introducing "promises". · postgres/postgres@fd333bc · GitHub
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Speed up plpgsql trigger startup by introducing "promises".
Over the years we've accreted quite a few special variables that are predefined in plpgsql trigger functions. The cost of initializing these variables to their defined values turns out to be a significant part of the runtime of simple triggers; but, undoubtedly, most real-world triggers never examine the values of most of these variables. To improve matters, invent the notion of a variable that has a "promise" attached to it, specifying which of the predetermined values should be assigned to the variable if anything ever reads it. This eliminates all the unneeded startup overhead, in return for a small penalty on accesses to these variables. Tom Lane, reviewed by Pavel Stehule Discussion: https://postgr.es/m/11986.1514407114@sss.pgh.pa.us
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-142
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5 files changed

+306
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‎src/pl/plpgsql/src/pl_comp.c

Lines changed: 38 additions & 12 deletions
A3D4
Original file line numberDiff line numberDiff line change
@@ -607,79 +607,99 @@ do_compile(FunctionCallInfo fcinfo,
607607
-1,
608608
InvalidOid),
609609
true);
610-
function->tg_name_varno = var->dno;
610+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
611+
var->dtype = PLPGSQL_DTYPE_PROMISE;
612+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_NAME;
611613

612614
/* Add the variable tg_when */
613615
var = plpgsql_build_variable("tg_when", 0,
614616
plpgsql_build_datatype(TEXTOID,
615617
-1,
616618
function->fn_input_collation),
617619
true);
618-
function->tg_when_varno = var->dno;
620+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
621+
var->dtype = PLPGSQL_DTYPE_PROMISE;
622+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_WHEN;
619623

620624
/* Add the variable tg_level */
621625
var = plpgsql_build_variable("tg_level", 0,
622626
plpgsql_build_datatype(TEXTOID,
623627
-1,
624628
function->fn_input_collation),
625629
true);
626-
function->tg_level_varno = var->dno;
630+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
631+
var->dtype = PLPGSQL_DTYPE_PROMISE;
632+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_LEVEL;
627633

628634
/* Add the variable tg_op */
629635
var = plpgsql_build_variable("tg_op", 0,
630636
plpgsql_build_datatype(TEXTOID,
631637
-1,
632638
function->fn_input_collation),
633639
true);
634-
function->tg_op_varno = var->dno;
640+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
641+
var->dtype = PLPGSQL_DTYPE_PROMISE;
642+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_OP;
635643

636644
/* Add the variable tg_relid */
637645
var = plpgsql_build_variable("tg_relid", 0,
638646
plpgsql_build_datatype(OIDOID,
639647
-1,
640648
InvalidOid),
641649
true);
642-
function->tg_relid_varno = var->dno;
650+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
651+
var->dtype = PLPGSQL_DTYPE_PROMISE;
652+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_RELID;
643653

644654
/* Add the variable tg_relname */
645655
var = plpgsql_build_variable("tg_relname", 0,
646656
plpgsql_build_datatype(NAMEOID,
647657
-1,
648658
InvalidOid),
649659
true);
650-
function->tg_relname_varno = var->dno;
660+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
661+
var->dtype = PLPGSQL_DTYPE_PROMISE;
662+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_TABLE_NAME;
651663

652664
/* tg_table_name is now preferred to tg_relname */
653665
var = plpgsql_build_variable("tg_table_name", 0,
654666
plpgsql_build_datatype(NAMEOID,
655667
-1,
656668
InvalidOid),
657669
true);
658-
function->tg_table_name_varno = var->dno;
670+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
671+
var->dtype = PLPGSQL_DTYPE_PROMISE;
672+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_TABLE_NAME;
659673

660674
/* add the variable tg_table_schema */
661675
var = plpgsql_build_variable("tg_table_schema", 0,
662676
plpgsql_build_datatype(NAMEOID,
663677
-1,
664678
InvalidOid),
665679
true);
666-
function->tg_table_schema_varno = var->dno;
680+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
681+
var->dtype = PLPGSQL_DTYPE_PROMISE;
682+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_TABLE_SCHEMA;
667683

668684
/* Add the variable tg_nargs */
669685
var = plpgsql_build_variable("tg_nargs", 0,
670686
plpgsql_build_datatype(INT4OID,
671687
-1,
672688
InvalidOid),
673689
true);
674-
function->tg_nargs_varno = var->dno;
690+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
691+
var->dtype = PLPGSQL_DTYPE_PROMISE;
692+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_NARGS;
675693

676694
/* Add the variable tg_argv */
677695
var = plpgsql_build_variable("tg_argv", 0,
678696
plpgsql_build_datatype(TEXTARRAYOID,
679697
-1,
680698
function->fn_input_collation),
681699
true);
682-
function->tg_argv_varno = var->dno;
700+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
701+
var->dtype = PLPGSQL_DTYPE_PROMISE;
702+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_ARGV;
683703

684704
break;
685705

@@ -701,15 +721,19 @@ do_compile(FunctionCallInfo fcinfo,
701721
-1,
702722
function->fn_input_collation),
703723
true);
704-
function->tg_event_varno = var->dno;
724+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
725+
var->dtype = PLPGSQL_DTYPE_PROMISE;
726+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_EVENT;
705727

706728
/* Add the variable tg_tag */
707729
var = plpgsql_build_variable("tg_tag", 0,
708730
plpgsql_build_datatype(TEXTOID,
709731
-1,
710732
function->fn_input_collation),
711733
true);
712-
function->tg_tag_varno = var->dno;
734+
Assert(var->dtype == PLPGSQL_DTYPE_VAR);
735+
var->dtype = PLPGSQL_DTYPE_PROMISE;
736+
((PLpgSQL_var *) var)->promise = PLPGSQL_PROMISE_TG_TAG;
713737

714738
break;
715739

@@ -1878,6 +1902,7 @@ build_row_from_vars(PLpgSQL_variable **vars, int numvars)
18781902
switch (var->dtype)
18791903
{
18801904
case PLPGSQL_DTYPE_VAR:
1905+
case PLPGSQL_DTYPE_PROMISE:
18811906
typoid = ((PLpgSQL_var *) var)->datatype->typoid;
18821907
typmod = ((PLpgSQL_var *) var)->datatype->atttypmod;
18831908
typcoll = ((PLpgSQL_var *) var)->datatype->collation;
@@ -2196,6 +2221,7 @@ plpgsql_finish_datums(PLpgSQL_function *function)
21962221
switch (function->datums[i]->dtype)
21972222
{
21982223
case PLPGSQL_DTYPE_VAR:
2224+
case PLPGSQL_DTYPE_PROMISE:
21992225
copiable_size += MAXALIGN(sizeof(PLpgSQL_var));
22002226
break;
22012227
case PLPGSQL_DTYPE_REC:

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